Recovery of carbon black from suspension in a gas



Feb. 12, 1952 M. o. KILPATRICK RECOVERY CARBON BLACK FROM SUSPENSION IN A GAS 2 SHEETS- SHEET l Filed March 25, 1946 lllll ll lllll mdmm N Kuba? 2 SHEETS-SHEET 2 INVENToR. MD. KILPATRCK ATTORNEYS Feb. l2, 1952 M. o. KlLPATRlcK RECOVERY OF CARBON BLACK FROM SUSPENSION IN GAS Filed March 25, 1946 Patented Feb. l2, 1952v RECOVERY OF CARBON BLACK FROM SUSPENSION IN A GAS Myron O. Kilpatrick, Bartlesville, Okla., assignor to Phillips Petroleum Company, a corporation of Delaware Application March 25, 1946, Serial No. 656,964

This invention relates to the recovery of carbon black from suspension in a gas and more particularly to a process for the recovery of carbon black from the eiiluent (known in the art as smoke) of a furnace type reactor chamber which is employed for making the type of carbon black known as furnace black. Still more particularly it relates to a process of the foregoing type which accomplishes removal of the carbon black as a slurry in an aqueous liquid medium.

In the process for making carbon black by the furnace type method, a liquid or gaseous hydrocarbon is fed into a reactor, or combustion chamber, along with a controlled quantity of air. The product off one of these reactors contains large quantities of gases (hydrogen, water vapor, carbon dioxide, etc.) and solid particles of carbon black. This stream leaves the reactor between 2000 F. and 3000 F. and is usually cooled immediately to between 1000 F. and 1500o F. by a water quench. In the conventional recovery process the carbon black containing stream is further cooled in a secondary quench to between 300 F. and 600 F. before entering a Cottrell precipitator where the carbon black is retained and/ or agglomerated by the electrodes of the precipitator.

The principal objects of the present invention include the following: ('1) To provide an improvedy method of recovering carbon black from suspension in a gas; (2) To provide an improved method of recovering carbon black from'combustion products of a carbon black furnace; (3) To provide an improved method of recovering furnace carbon black from smoke; (4) To reduce or eliminate the need for using expensive Cottrell precipitators or Iunsatisfactory filters; (5) To provide a process whereby the carbon black is recovered as a slurry in an aqueous liquid medium; (6) to recover the rcarbonblack as a slurry in water; (7) rTo recover the carbon black as, a slurry in rubber latex; and (8) To form a concentrated slurry of the carbon black. Numerous other objects will hereinafter appear.

In the accompanying drawings:

Fig. 1 portrays diagrammatically one arrangement of equipment which is very satisfactory for carrying outmy invention as applied to the recovery of furnace black,

24 Claims. (Cl. 23-1209.8)

mately contacting the gas with an aqueous liquid medium. This contacting is carried out. under such conditions that the carbon black particles are wetted by the aqueous liquid medium and caused to leave the gas and become suspended, forming an aqueous carbon black slurry.

' My invention is applicable to any suspension of carbon black in a gaseous medium; whether said suspension be the effluent from a carbon black producing process or whether said suspension be formed from previously produced carbon Fig. 2 portrays a modification of the scrubbing black by suspending same in a gaseous stream. For example, it is old to unload dry unpelleted carbon black from tank cars by sucking same into a stream of gas, such as air, using equipment known as a pneumatic conveyor. This causes the formation of a suspension of the carbon black in the gas. My invention may be employed to separate the carbon black from such a suspension.

My invention is especially applicable in the recovery of carbon black from the combustion products or smoke issuing from a unit making furnace black. As is well known, furnace black is made by subjecting a suitable hydrocarbon uid such as gas oil or natural gas to incomplete combustion in the presence of a limited amount of oxygen. Usually a secondary stream of hydrocarbon fuel and air is charged to the furnace to bring about the-desired reaction. Examples of production of furnace black are given in U. S. Patents Yto Krejci 2,375,795 and 2,375,796.

` The concentration of carbon black in the smoke stream issuing from a furnace type reactor such as that disclosed in the Krejci patents just mentioned averages about .39 grains per standard cubic foot dry. This is an l extremely small amount of suspended carbon black on a weight or volume basis. This illustrates the magnitude of theproblem which confronted applicant.

Any suitable aqueous liquid may be used as the scrubbing medium employed in practicing my invention. The particular aqueous medium selected will depend, of course, upon the type of slurrydesired. Water is often preferred. Water gives a carbon black-water slurry which can be used very successfully in copolymerization plants for incorporation in synthetic rubber latex just prior to coagulation. For example, by erecting a furnace type carbon black plant adjacent to or in conjunction with a copolymerization plant and employing `my invention, the carbon black can be recovered from the furnace gases by means of water, thereby eliminating very expensive Cottrell precipitatorsand complicated carbon black vis very inconvenient and troublesome.

ventional practice the carbon blackiisfqreeovered:

by an electrical precipitator, then densed; thenl pelleted, finally packaged, and shipped to the,v destination. My invention eliminates alljo these steps. It is obviously much simpler and cheaper to transport the fuel, such as gas or oil, to the destination and there convert it -intocarbon-blackf slurry in accordance with my invention.. than making the carbon blackg at one point and shipping Lit to the pointlwhere it is tombe used,

Where water is used for formingthe-slurry,y .it is i preferable ,that itbe hotpinaslnuohy as .the black is more readily wetted by hot water.. The temperature of the water is preferably at least 140 F.; ranging upwardly therefrom to the boiling point. The nearer thetemperature is to the boiling-point of the water, thebetter is the wetting, the more easily is-the slurry'form-ed, and the more complete is the-removal of the carbon black from the gas.

In most-cases the 'water-should betreatedfin any suitablemanner to free it from-objectionable or harmful compounds. For example, deionized Water maybe used. Useof treated wateris ad'- vantageous since it eliminates Vobjectionable effects` during the-s1urry-formation andI during mixing' of the resulting 'slurry with rubber latex. If untreated water isI employed; calcium andmagnesium soapsfare formedwhen the slurry.. is

commingled with the latex. Latex generally contains water-soluble soaps; These soaps .Y react Vwith the1 calcium and magnesium in the slurry madey with untreated Water. tos form insoluble soaps which are highly undesirable.

I'generally prefer to add Ytoethegwater orfother. aqueous liquid scrubbing .-mediuma wettingf.agent which promotes the wetting; offthercarbonzblackby` the water orV otherrmediumi This agent-may `alsofimotion-.as ai-dspersing osntrforftheacarbon, holdingv the carbon; blaolciin: suspension in the'aqueous medium, Y

Any suitablewettingagentgmayfbe-used;` The preferredf wetting: agentv isgD.afX&.d:1l,- afcommercial; material Inanufactui'edt by- Deweyy and Y Almy- Chemical. Company. This material may. be

thoalkali metolsalts thereof. .made,..for. example. by, condensing., benzene-. with.. chlorinated.; kero.-

senein thepresence of a Friedel-Crafts catalyst,` such as AlClavor by'alkylatingaromatics in any otherl suitable manner, Yandjsulfonatingl they resulting alkylated 'aromaticon the ring.

Instead of the'wetting agents setforth-'in the preceding` paragraph; I1' mayuseother-materials alkali metal salts of long-chain fatty acids) or certain bark extracts such as those known as saponin. However, the bark extracts like saponin are generally unsatisfactory because they show an extreme foaming tendency. Unless some means is employed to allay this.tendencyasaponin cannotbeusedinvmany cases.

I prefer to use those wetting agents which show little or no foaming tendency.

In, many.I cases, especially where the smoke streamwisat a temperature of from 300 to 600 F. or higher when it contacts the aqueous slurryformingvmedium, Ind it highly desirable to useV an anti-foaming agent. For example, the

. anti-foaming agents disclosed in Craig U. S.

Batentp2,3 62,052, may be employed. Any other suitable means known to the art or hereafter discovered for suppressing foaming of the aqueous liquid medium may be employed. Use ofan. anti-foaming agent may be imperative when certain wetting agentsare employed:

TheV amount-:of thev 'wettingV or dispersing: agent employed may vary within wide limits,. forexample, from 0V to A5 per centsby weightbasedfon the-carbon black ultimately suspendedfin; theslurry. A preferred range is from 2 to-.S pergcent by 4weight based on the Weight of black. Itshould beemphasizedthat these igures refer to the weight of black-only. Forv example, in av25fper centslurryfwith 3 percent offwettingagent; there would-be 0.75f-per centof thewettng agent-ing thefcomposite slurry.

Not every typeA of carbon black: requiresA a wetting agent.- Certain types -ofj carbon black arefknownwhich will actually Sizzle when contacted--With Vwater and thus no .wetting agent-is required .in Vsuch cases `to. .produce a slurry.

Ihave found that once a slurry -is started, that is.; as soonas Ysome quantity of carbonblackhas been thoroughlyy wetted, that additional -quantities of black are readily dissolvedor Wettedfby the-slurry. In fact,l withffurnaceblack of'the type known as Philblack produced in accord.-v anceywith-Krejci U. S. Patent2,375,796, a slurry formed with water and a wettingy agent-Will. literally suck additional quantities of carbon blackinto the slurry.

This. discovery may be, taken advantage of. inaccordance with apreferred embodiment of my invention. Thus, the. aqueous carbon black slurry. may. be withdrawnfrom the contacting zonefor example, from the bottom of avertical scrubing. zone, andl split into.l two., streams..,one aproduct ,slurry4 stream ,and the other a recycle stream.A This recycle/stream mbe pumped back intothe contacting z one for further con,-v taotin accordance with .the discovery.. that-once, slurrying. has .been initiated. additional vSlurn'irllf; is v eryrapid.;

Recyclingof slurry infthe mannerA just def-V scribed, for additional, slurrying enables a higher concentration of carbon black in the product slurry to be attained. In this waythe carbon black may be caused to attain a levelof from l() to 25 per cent by weightof the slurry, ina simple and economical manner.

Generallyl the recycle stream of slurry. substantially predominates over the productstream. In many cases the recycle stream may constitute as -much as per cent and the product stream as little ,as 10 per cent of the slurrystreanl withdrawn from the contacting zone. In any event.. I prefer that the recycled slurry stream be!` at least" 5' timesY as. great as the product-slurry stream.

When a vertical countercurrent contactor" is employed, I may inject the recycled slurry stream:

into the scrubbing zone at a point intermediate the points of introduction of the fresh aqueous liquid and the incoming smoke. I may introduce the recycled slurry at a point adjacent the topA of the scrubber but substantially below the point at which the fresh medium is introduced- In this I way the outgoing gas is finally scrubbed/with;

. Y 1 10 It may be preferable to recycle the slurry into y admixture with the fresh incoming aqueous liq-4 uid, thereby obtaining the advantage of more rapid slurrying by reason of slurrying .having fresh liquid.

been initiated. In this way I may take. advantage of the discovery, mentioned above, thattrans'fer; of carbon black from gaseous suspension toga;A preformed slurry, even though it may have ayloyv;l

carbon black concentration, is much more rapid than transfer to an aqueous medium containing no carbon black slurried therein.

In .many cases it may be preferred -to dividel the recycled slurry stream into two portionsg-thei major portion being introduced into thescrub-- bing Zone at a point substantiallybelow lthe'point of introduction of the fresh aqueous medium,

and the minor portion being admixed intimately with said fresh medium prior to introduction thereof into the top of the scrubbing zone.` .In

this way the advantages of having a high carbonv black concentration in the lower part of'v the scrubbing zone and of having a low but substantial carbon black concentration in the-aqueous medium which contacts the gases leaving the scrubber are attained. Y

It will be obvious that the product slurry stream is withdrawn from the system at a rate corresponding to that at which fresh aqueousmedium is introduced to the contacting zone. kThis-is true regardless of the magnitude of the carbon black concentration maintained in the slurryin the endless cycle or recirculating system and regardless of whether the recycled slurry stream is admixed with the incoming fresh aqueous medium or is introduced into the contactor at a point be- W the incoming fresh medium; i

It will also be obvious that while `thel carbon black concentration of the slurry thatis recycled is identical with that of the product slurry stream,

and transportation, the less the dilutiontwhenlthev slurry is mixed with rubber latex, and the less. the expense of Water removal at -therubber plant. x

In order to form slurry concentrationsin; excess of 10 per cent, a wetting or dispersing'agent is practically essential in order to maintain a pump-5 able slurry. When hot water only -itused,=.the.

slurry begins to have a body at approximately 7 to 8 per cent concentration and the viscositynf this slurry increases rapidly at a concentration of 10 per cent. If viscosity is plotted as :the ordinate against concentration as the abscissa,the` curve breaks from a horizontal to an almost verti:'- cal plane at 10 per cent. By the use of approxi-` mately 3 per cent of wetting agent (based on the ultimate weight of carbon black of per cent) in the water, however, theviscosityl of the slurryy may be maintained at a low value and practically constant until a concentration of about: 2541er;`

cent is obtained. At this point the conditionjust noted for 10 per cent slurry with no wetting agent repeats itself. The preferred concentration of carbon black in the product slurry, when a wetting agent is used, is 15 to 25 per cent. When water without a wetting agent is employed, the preferred ultimate carbon black concentration in the slurry is 8 to 10 per cent. All concentrations given in this specification are by weight.

It -will be seen that the wetting or dispersing agent serves two very important purposes, at least with respect to most carbon blacks. The rst purpose is to increase actual efciency of wetting the black, and the second purpose is to effect viscosity control of the slurry. As pointed out above, all blacks do not require such agents for:`v wetting only, but all blacks do require such agents for keeping slurry viscosity low provided the 10 per cent concentration gure is exceeded.

In applying my invention to the recovery of carbon black from the smoke issuing from a furnace type of reactor, I apply the conventional primary quenching with water to the hot gaseous effluent leaving the reactor at 2000 to 3000 using an amount of water such that its temperature is reduced to between 1000 and 1500 F. The water used for this quenching is entirely vaporized. The resulting carbon black stream may be given a further or secondary quenching to a temperature of 300 to 600 F. and may then enter the scrubbing step. Where water is used as the scrubbing agent, the temperature of the gases fed to the scrubber is relatively'immaterial and may range from 300 to l500 F.

Where rubber latex is used instead of water asl the liquid contacting medium, there may be danger of coagulation of the latex Within the contacting equipment, especially at high temperatures. When latex is used, I prefer to employ a secondary quenching to a temperature below 300 F., with water as the quenching medium. To avoid coagulation of the latex it may be desirable to lower the temperature of the smoke stream to as 10W as 100 F. A temperature of from 100 F. to 250 F. is preferred. The quenching of the smoke stream with water to a temperature within this range is difficult because in so doing a liquid' water phase is formed in the quenching operation with the result that the quenching equipment and immediate lines become plugged or mudded up with partially wetted carbon black."

It is impossible to attain this degree of quenching without direct contact with water and the resulting liquid phase. In order to overcome this difficulty I prefer, when using latex as the slurryforming medium, to carry out the secondary quenching step, or at least that portion ofthe,

quenching which lowers the temperature of the smoke below the boiling point of wateryin they base of the latex contactingequipment. I mayY do this by injecting liquid water, containing a wetting agent or not, into the smoke just before it enters the bottom of the contactor and may inject liquid water at a point substantially above the Apoi-nt of entry of the smoke. The Water so introduced mayor may not contain a wettingagent, and may or vmay not be commingledwith a small amount of recycled slurry in order to promote wetting of the carbon black and re-;

moval from the gas. The liquid latex descends through the zone and merges with and picks up4 the water-carbon black mixture formed in the secondary quenching zone. The resultingzlatexcarbon black slurry is somewhat diluted bythe water, but Il am careful to limit the amount of abastece:

1 waterintroducedso that dilution of the slurry is notv excessive. And by appropriately recycling slurry as explained above I can attain the desired high carbon black concentration even though the slurrynecessarily contains less rubber in relation to waterthan it would were no water introduced. However. this objection is outweighed by the fact that this type of operation l enables me to obtain directly a slurry of carbon black in latex without coagulating or otherwise injuring the latex and without plugging ofsecondary quenching equipment. Y

As in the case of water, I may recycle a major portion of the slurry in latex withdrawn from the bottom of the'scrubber. This may be recycled entirely into the scrubber at a point substantially below the top thereof. Or it may be recycledentirely into admixture with the latex fed into the top. As before, however, I often prefer to introduce a major proportion of the recycie stream into the upper portion below the fresh latex and a minor proportion thereof into admixture with the fresh latex introduced at the top.

The rubber latex may be either natural or synthetic. The use of synthetic rubber latex in practicing my invention is especially advantageous.

Y This eliminates the necessity of pumping the re- By locating the carbon black furnace in juxtaposition to a rubber copolymer plant, the synthetic latex may be pumped from rubber plant to ther carbon black plant and there employed to recoverfthe carbon black, the resulting slurry of carbon black being pumped back to the rubber plant for coagulation and further processing in the usual manner.

The rubber latex may already contain a wetting agent. For example, in the emulsion polymerizationv process of making synthetic rubber, it is necessary to use an emulsifying agent for emulsifying the monomeric materials in the aqueous phase. Examples of materials which have been employed in the production of vsynthetic rubbers are the well-known soaps, such as sodium oleate, sodium stearate, etc.; and the well-known wetting agents, such as sulfonated mineral oils, organic sulfonic acids, saponin, etc. yIhe emulsifying agent which was adapted as standard in the GR-S rubber program was pure water soluble soap. Y

The wetting agent already present in the rubber latex Vmay serve as the wetting agent for facilitating for wetting with the carbon black with the latex in practicing my invention. Alternatively, an extraneous or additional wetting agent,

such as those described in detail in the early porf tionY of this specification, may be introduced into thev rubberv latex before it is employed to recover carbon black from suspension in a gas in accordance with the present invention.

In order to effect intimate contact between the carbonblack-laden gas stream and the aqueous liquid scrubbing medium, any suitable equipment may be used. In some cases a vertical contacting tower is employed, the aqueous liquid medium being introduced at the top and the smoke being injected into the bottom. This tower is preferably provided with baffles or other suitable Vcontacting means. @The carbon black-laden gas passes upwardly in countercurrent to the aqueous scrubbing medium. Instead of baffles,` packing may be employed for promoting intimate contact between gas and liquid.

Insome cases, it may be preferred to employ concurrent' contact of the carbon black-laden gas and the aqueousliquid medium.. This: is especially desirable when requipment such as that known in industry as a Roto-Clone is employed.

cycled slurry to achieve the desired concentration, since the Roto-Clone gives-the final ccncentration in a once-through operation.

Instead of the contacting equipment described above, mechanical washers of any known type for scrubbing very small dispersoids from a gas stream may be employed.

l The gaseous eiiluent from the contacting chamber may be passed through a Cottrell precipitator, bag filter, or any other suitable device for removing last traces of carbon black.

The carbon black slurry made by my invention is preferably passed through a Wet grinder or pulverizer in order to produce a more uniform particle size carbon black and a slurry which is smooth and free from graininess.

In Fig; 1 of-'the drawings', the oil or gas to be converted into furnace carbon black enters reactor I via line 2. Reactor I is shown schematically only. It will be understood that fuel and air must be'introduced to reactor I in orderk to..

provide the necessary heat for decomposition.

It will also be understood that the oil or gas feed owing in line 2 is subjected to limited combustion with a controlled amount of air and thereby converted to carbon black in the known manner. Thel reaction gases containing the carbon black in suspension leave through the header 3 and are subjected to primary quenching in portion li by means of liquid water injected via line 5. The resulting gaseous stream which is now ata temperature of from 1000 to 1500 F. passes via line 6 either-to separatesecondary quenching means 1, orvia bypass line 8 directly into the bottom oft contacting chamber 9. If secondary quench tank 'I is not employed, I prefer to carry out secondary quenching in the bottomof unit 9, especially in the case where latex is usedas the scrubbing medium instead of water.

Unit Y9 is a vertical contacting tower equipment With the usual sloping baffles to promote intimate contact between the ascending gas and the descending aqueous scrubbing medium. The scrubbing medium is introduced via line Ii] to the top of unit 9'. The scrubbed gases leave via header II whence theyarepassed to a Cottrell precipitator, a bag lter, or to the air.

As the aqueous scrubbing medium descends in unit 9; it wets thefcarbon blackparti'cles suspended in the gas thereby causing them to leave thegas and become suspended in the aqueous liquid, forming an aqueouscarbon black slurry. This slurry leaves the bottom of unit 9 via line I2. I prefer to split this stream into two portions, the major portion being recycled to unit via line i3 and pump I4, and aminor portion being-'withdrawn via line I5. The portion flowing in line I5 constitutes the product of my process. I prefer to pass it through Wet pulverizer IS in order to grind any coarse particles to a iine state of subdivision and remove any graininess, thereby giving a smooth, uniform slurry which is withdrawn via line I1.

l The recycled slurry vmay be entirely reintroduced into the contactor 9 via line I8. Alterna-- tively, it may be entirely passed via line ISinto a'dmixture with the incoming aqueous liquid medium owing in line III. I prefer, however, to introduce a major portion of the recycled slurry via line I8 and to .admix a minor portion thereof.

with the-fresh aqueous medium continuously enteringrthe system via line I0. Any meanssuch as:

a conventional mixing T may be employed to effect intimate and homogeneous admixture of the slurry introduced via line I9 with the fresh liquid flowing in line IU prior to introduction o the mixture into unit 9.

When latex is employed as the scrubbing medium, it is desirable that a secondary quenching be employed in order to reduce the temperature of the gases contacting the latex to a suitable low temperature.A While this secondary quench may be carried out with liquid water introduced into secondary quench tank 1, I much prefer to dispense with tank and to inject the relatively hot smoke directly into the bottom of unit 9, the secondary quenching being carried out in the-lower portion of unit 9. Liquid water ispreferably introduced via line 20 directly into the smoke stream just prior to its entry into unit 9. Liquid water is also introduced Via line 2| into unit 9 at a point substantially above the bottom thereof.VV In this way the smoke stream is secondarily quenched to a relatively low temperature, say 250o` F., before it enters the portion of unit 9 above the point of entry of pipe 2|. In order to initiate wetting by the water injected in line 2|,

ya small portion of the recycle slurry stream may be intimately admixed therewith prior to' introduction into unit 9. By proceeding in the manner just described, any tendency to plug in the secondary quenching section of the equipment is eliminated since theV downwardly descending latex wets and washes out any partially wetted carbon .black and incorporates same into the latex slurry issuing via line I2.

In the unit shown in Fig. 2 of the drawing, a closed chamber 3| which is square or rectangular in horizontal cross-section is provided. The

smoke enters through opening 32 at the r'ear of the unit near the top of a fixed guide member 33 which'has depending sides 34 which extend downwardly and at the bottom where they are close to the liquid level and on the outer faces they are provided with curved means which coact with thecurved surfaces of xed means 35 in such a way that the gas picks upa sheet of the liquid Vas it passes between the curved faces and throws the sheet in such a way that it very intimately contacts it, thereby eecting removal of nearly all of the carbon black (say 96 per cent) and `formation of a carbon black slurrry in the bottom lof chamber 3|. The resulting mixture of gas and liquid is thrown violently into the liquid between member 33 and the right and left walls of cham ber 33, in the manner indicated in the drawing. The gas separates from the `liquid and passes upwardly 'through bailles 36 which serve to knock out entrained liquid. If desired water, contain;- ing a wetting agent or not and having-a little carbon black dispersed therein or not as desired, may be sprayed onto the upper faces of bailles 36 by means of pipe 3l if desired to remove any remaining carbon black in suspension in the gas. A fan 38 may be employed, if desired, to pull the gas through out of the unit and reduce the pressure therein.

Fresh aqueous medium is continuously introduced via line 39 and iinished slurry of the desired concentration is continuously withdrawn'via line 40 at a corresponding rate such as to maintain the volume and level of the liquid in unit v3| constant. It will'be obvious that if desired floatcontrolled means may be provided for holding the liquid level in the bottom of unit 3| vconstant and at the proper point with respect to the curved surfaces which form the curtain of liquid.V The 10 liquid may be any of those disclosed in detail herein and the foregoing disclosure is applicable to Fig. 2 equally as to Fig. 1.

I claim:

1. The process of recovering carbon black from suspension in a gas whichcomprises intimately scrubbing said gas containing carbon black in suspension with an aqueous liquid medium containing anadded wetting agent and thereby causing the carbon black particles to leave said gas and become suspended in said aqueous liquid medium 4and form a liquid aqueous carbon black yslurry. withdrawing the resulting liquid slurry medium 'consists essentially of water.

4. The continuous process of making furnace carbon black which is diiiicultly wettable with water and recovering same inthe form of an aqueous slurry which comprises subjecting a hydrocarbon'fluid toincomplete combustion under vsuch conditionsas to produce a gaseous effluent containing solid 'particles of carbon black in suspension, quenching the resulting hot gaseous effluentk withwater, passing the resulting effluent upwardly in a vertical scrubbing zone and in intimate'countercurrent contact with an aqueous liquid mediuml containing an added wetting agent, introducing a fresh supply of said aqueous mediumv containing said added wetting agent into the top of said scrubbing zone, causing said carbon black particles to leave said eilluent and become suspended in `said aqueous liquid medium and form 'a' liquid aqueous carbon black slurrry, withdrawing the resulting liquid slurry from the bottom of ,said zone, splitting the withdrawn slurry into a relatively large stream and a relatively small'stream, 'recycling the relatively large stream4 withoutthe removal of the major portion of the vcarbon black from said slurrry and introducing a majoriportion thereof into said scrubbing lzone at a point intermediate the points of introduction of said fresh aqueous medium convdifficulty of wetting of said carbon black with water is overcome, and withdrawing said relatively small' streamifrom the system as the product of the process.

5. The Vprocess of clairn4 wherein saidaqueous medium is rubber latex. y

6. The process of claim 4v wherein said aqueous mediumL consists essentially of water.

'7. The continuous process of making furnace carbon black which is'difcultly wettable with water and recovering same in the form of a slurry in rubberilatex which comprises subjecting a hydrocarbon fluid to incomplete combustion under such conditions as to produce a gaseous efuent containing solid"l particles vof carbonv black in suspension, quenching the resulting hot gaseous eilluent with water toa`v temperature of` from 300 at a point adjacent butsubstantially above the `point at which said elliuent enters same and causing same to descend in intimate countercurrent contact with said eluent, carrying' out `secondary quenching of said ellluent with said water in the lower portion of said zone, introducing y rubber latex into the top of said zone and causing same to descend therein in intimate countercurrent contact with said eluent, causing the carbon particles to leave said ellluent and become suspended in said water and said latex and form a liquid slurry and withdrawing the resulting liquid slurry of carbon black in latex from the bottom of said zone, said slurry embodying the latex and the water injected into said zone.

8. The process ofclaim '7 including the further steps of splitting the withdrawn slurryinto two streams, one relatively large and one relatively small, recycling said relatively large stream without the removal of the major portion Aof the car- `bon black from said slurry and introducing Same Y into the upper portion of said ,scrubbing zone and withdrawing said relatively small stream as the product of the process.

9. The process of claim 7 including the further steps of splitting the withdrawn slurry into two streams, one relatively large and one relatively small, recycling said relatively large stream without the removal of the major portion ofthe carbon black from said slurry to said scrubbing zone, admixing a relatively small portion thereof with the latex introduced to the top of saidscrubbing zone and introducing a relatively large portion thereof into said scrubbing zone at a point adjacent but substantially below the top thereof, and withdrawing said relatively small slurry stream as the product of the process, said last-named stream corresponding in amount to the amounts of water and latex fed to said scrubbing zone.

. 10. The process of recovering carbon black from suspension in a gas which comprisesintimately l `scrubbing said gas containing carbon yblack .in

suspension in an aqueous liquid medium containing a minor buteiective amountof a wetting agent comprising an alkali metal .alkylaryl sul- `fonate to form an aqueous carbon black slurry,

withdrawing the slurry from the scrubbing zone,

splitting the withdrawnslurry into two streams, recycling one of said streams to `said scrubbing step to cause the concentration of carbon black in the withdrawn slurry two attaina level of from 10 to 25 per cent by weight, and withdrawing the other stream of slurry from the system as the product of the process.

11. The process of recovering carbon black from suspension in a gas which comprises `intimately scrubbing said gas containing carbon black in suspension in an aqueous liquid medium containing 1 to 5 per cent of a wetting agent based on the weight of the carbon black comprising an alkali metal alkylaryl sulfonate to form an aqueous carbon black slurry, withdrawing the `slurry from the scrubbing zone, splitting the .withdrawn slurry into two streams, recycling one of said streams to said scrubbing step to cause the concentration of carbon black in the withdrawn slurry to .attain a level of from 10 to 25 percent by weight, and withdrawing the other stream of slurry from the system as the product of the process.

12. The process of recovering carboniblack from 12 .suspension in @a ses which '.Qompr-.isesv-rintimately scrubbing said gas-containing carbongblackin suspension in an aqueous liquid medium containing a minor but veiiective amount of ja wetting agent comprising an alkali metal u,al-kylieenzene sulfonate to -form an aqueous carbon ,black slurry,

l Suspension ina gas vwhich comprises `intiniately .scrubbing said gas containing carbon black .in

`suspension in an aqueous liquid medium containing 1 to 5 per cent of a wetting agent based on the `weight of the carbon black comprising .an alkali metal alkylbenzene -gsulfonate ,to forman aqueous `carbon black slurry, withdrawing .the slurry from thel scrubbing zonefsplitting the withdrawn slurry into two streams, recycling one of said streams to saidscrubbing step `to cause the concentration of carbon black in the withdrawn .slurry to .attain-a level of from 10 to 25 percent by weight, and withdraw-ing the otherstream-of `slurry -from -the system as the product ;of `.the

process.

14. The Lprocess. of recovering carbon black from suspension in a gas ywhich -ecmprises intimately scrubbing said gas containing 4carbon .black in suspension in an aqueous liguidmedium contain- Ving aminor but effective amount of a wetting agent comprising an alkali :metal alkylnaphthalene sulfonate to form an aqueous carbon black slurry, withdrawing the slurry .from the scrubbing zone, splitting the withdrawn .slurry Vinto two streams, recycling Vone of Y,said streams .alkali metal alkylnaphthalene isulfonate to .form an :aqueous Carbon black .Slurmwthdrawing ,the

slurry from the scrubbing 2011., .Splitting the with.- Vdrawn slurry into two streams, 4recyclinglone fof said streams to said lscrubbingstep to -cause .the

`concentration of carbon black in thewithdrawn slurry toattaina level of ,from 10 to v25 -per cent by weight, Vand withdrawingthe othervstream of slurry from the system as thgejproduct of the process.

v16. The process of` recovering carbon blackfrom suspension in a gas which comprisesintimately scrubbing said gas containing carbon lblack in suspension in an aqueous liquid mediumicontaining a minor fbutefective .amount .of ...a wetting vthe scrubbing zone,

slurry from the system as the product of the process.

17. The process of recovering carbon black from suspension in a gas which comprises intimately scrubbing said gas containing carbon black in suspension in an aqueous liquid medium containing 1 to 5 per cent of a wetting agent based on the weight of the carbon black comprising a polymerized sodium salt of isopropylnaphthalene sulfonic acid to form an aqueous carbon black slurry, withdrawing the slurry from the scrubbing zone, splitting the withdrawn slurry into two streams, recycling one of said streams to said scrubbing step to cause the concentration of carbon black in the withdrawn slurry to attain a level of from 10 to 25 per cent by weight, and withdrawing the other stream of slurry from the system as the product of the process.

18. The process of recovering carbon black from suspension in a gas which comprises intimately scrubbing said gas containing carbon black in suspension in an aqueous liquid medium containing a minor but effective amount of a wetting agent comprising an alkyl polyether alcohol to form an aqueous carbon black slurry, withdrawing v;

the slurry from the scrubbing zone, splitting the withdrawn slurry into two streams, recycling one of said streams to said scrubbing step to cause the concentration of carbon black in the withdrawn slurry to attain a level of from l to 25 per cent by weight, and withdrawing the other stream of slurry from the system as the product of the process.

19. The process of recovering carbon black from suspension in a gas which comprises intimately scrubbing said gas containing carbon black in suspension in an aqueous liquid medium containing 1 to 5 per cent of a wetting agent based on the weight of the carbon black comprising an alkyl polyether alcohol to form an aqueous carbon black slurry, withdrawing the slurry from splitting the withdrawn slurry into two streams, recycling one o f said streams to said scrubbing step to cause the concentration of carbon black in the withdrawn slurry to attain a level of from to 25 per cent by weight, and withdrawing the other stream of slurry from the system as the product of the process.

20. The process of recovering carbon black from suspension in a gas which comprises intimately scrubbing said gas containing carbon black in suspension in an aqueous liquid medium containing a minor -but effective amount of a wettingr agent comprising a water soluble alkali metal salt of a long chain fatty acid to form an aqueous carbon black slurry, withdrawing the slurry from the scrubbing zone, splitting the withdrawn slurry into two streams, recycling one of said streams to said scrubbing step to cause the concentration of carbon .black in the withdrawn slurry to attain a level of from 10 to 25 per cent by weight, and withdrawing the other stream of slurry from the system as the product of the process.

21. The process of recovering carbon black from suspension in a gas which comprises intimately scrubbing said gas containing carbon black in suspension in an aqueous liquid medium containing 1 to 5 per cent o1' a wetting agent based on the weight of the carbon black comprising a water soluble alkali metal salt of a long chain fatty acid to form an aqueous carbon black slurry, withdrawing the slurry from the scrubbing zone.

splitting the withdrawn slurry into two streams, recycling one of said streams to said scrubbing step to cause the concentration of carbon black in the withdrawn slurry to attain a level of from l0 to 25 per cent by weight, and withdrawing the other stream of slurry from the system as the product of the process.

22. The continuous process of making furnace carbon black which is difcultly wettable with water and recovering same in the form of an aqueous slurry which comprises subjecting a hydrocarbon fluid to incomplete combustion under such conditions as to produce a gaseous eilluent containing solid particles of carbon black in suspension, quenching the resulting hot gaseous eifluent with water, passing resulting eiiiuent upwardly in a vertical scrubbing zone and in intimate countercurrent contact with an aqueous liquid medium, introducing a fresh supply of said aqueous medium into the top of said scrubbing zone, causing said carbon black particles to leave said effluent and become suspended in said aqueous liquid medium and form a liquid aqueous carbon black slurry, withdrawing the resulting liquid slurry from the bottom of said zone, splitting the Withdrawn slurry into a relatively large stream and a relatively small stream, recycling the relatively large stream without the removal of the major portion of the carbon black from said slurry and introducing a major portion thereof into said scrubbing zone at a point intermediate the points of introduction of said fresh aqueous medium containing said added wetting agent and said resulting eiiiuent and a minor proportion thereof into admixture with said fresh aqueous liquid prior to introduction thereof into said zone whereby the diiculty of wetting of said carbon black with water is overcome, and withdrawing said relatively small stream from the system as the product of the process.

23. The process of claim 22 wherein said aqueous medium is rubber latex.

24. The process of claim 22 wherein said aqueous medium consists essentially of water.

MYRON O. KILPATRICK.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,707,775 Uhlinger Apr. 2, 1929 1,767,089 Miller et 'al Jan. 24,1930 1,765,991 Miller June 24, 1930A 1,801,436 Lewis Apr. 2l, 1931 1,902,746 Yunker Mar. 21, 1933 2,121,535 Amon June 21, 1938 2,123,482 De Jong July 12, 1938 2,163,630 Reed June 27, 1939 2,254,572v Harlow Sept. 2, 1941 2,288,087 Hanson et al. June 30, 1942 2,289,672 Merrill July 14, 1942 2,306,698 Heller Dec. 29, 1942 2,368,828 Hanson Feb. 6, 1945 FOREIGN PATENTS Number Country Date 114,040 Great Britain Mar. 21, 1918 429,088 Great Britain May 23, 1935 OTHER REFERENCES Lenher, Chemical Industries, March 1941, pages 324-326. 

1. THE PROCESS OF RECOVERING CARBON BLACK FROM SUSPENSION IN A GAS WHICH COMPRISES INTIMATELY SCRUBBING SAID GAS CONTAINING CARBON BLACK IN SUSPENSION WITH AN AQUEOUS LIQUID MEDIUM CONTAINING AN ADDED WETTING AGENT AND THEREBY CAUSING THE CARBON BLACK PARTICLES TO LEAVE SAID GAS AND BECOME SUSPENDED IN SAID AQUEOUS LIQUID MEDIUM AND FORM A LIQUID AQUEOUS CARBON BLACK SLURRY, WITHDRAWING THE RESULTING LIQUID SLURRY FROM THE SCRUBBING ZONE, SPLITTING THE WITHDRAWN 